Abstract 17063: The β-Subunit of the BkCa Channel Plays a Vital Role in Mediating Perivascular Adipose Tissue Induced Contractility in Isolated Small Arteries
Perivascular adipose tissue bestows a protective anticontractile effect on arteries. This is impaired in obesity where adipocytes become enlarged and hypoxic and aldosterone levels increase. BKCa channels hyperpolarise smooth muscle cells and reduce arterial constriction. This study explores the involvement of the β-subunit of BKCa channels in mediating the anticontractile properties of PVAT in isolated mesenteries arteries. Male and female, −/−BKβ1, C57BL/6 (Wild type) mice (12–18 week old ∼25g weight) were killed by stunning and cervical dislocation. Cumulative concentration responses (10−9-10−5M) to norepinephrine (NE) were performed before and after 10 minute incubation with aldosterone(5nM) ± eplerenone(5μM). Responses are expressed as mean (±SEM)% of KPSS constriction and analysed using 2-way ANOVA. NE produced a concentration dependent constriction of arteries. PVAT (n=10) significantly (P<0.05) reduced this constriction in wild-type vessels (Fig A). There are no significant differences in tension in arteries with PVAT (n=13) and arteries without PVAT (n=16) from −/−BKβ1 mice (Fig B). The responses in, −/−BKβ1 arteries were significantly (P < 0.05) less than in WT animals. Aldosterone abolishes the PVAT response in wild type arteries (Fig C). Eplerenone does not reverse the effects of aldosterone in wild type arteries with (n=7) or without PVAT (n=7). In −/−BKβ1 arteries, aldosterone significantly (P<0.05) increased tension in the presence of PVAT (n= 6) compared to corresponding control response (Fig D). This was reversed by eplerenone (n=7).This suggests that the β-subunit of BKCa channels mediates both PVAT and aldosterone responses in small arteries.
- © 2010 by American Heart Association, Inc.